As others have said, the issue is the store to the memory location in the array: x[i][j]. Here’s a bit of insight why: You have a 2-dimensional array, but memory in the computer is inherently 1-dimensional. So while you imagine your array like this: 0,0 | 0,1 | 0,2 | 0,3 —-+—–+—–+—- 1,0 | 1,1 … Read more
How to efficiently remove duplicates from an array without using Set
The accepted answer doesn’t explain the reason. Below are quoted from High Performance MySQL, 3rd Edition. In many database servers, IN() is just a synonym for multiple OR clauses, because the two are logically equivalent. Not so in MySQL, which sorts the values in the IN() list and uses a fast binary search to see … Read more
Based on this previous answer, the example below simulates a fleet of three cabs moving randomly on a rectangular grid. A javax.swing.Timer drives the animation at 5 Hz. The model and view are tightly coupled in CabPanel, but the animation may provide some useful insights. In particular, you might increase the number of cabs or … Read more
It’s pretty intuitive: A program is CPU bound if it would go faster if the CPU were faster, i.e. it spends the majority of its time simply using the CPU (doing calculations). A program that computes new digits of π will typically be CPU-bound, it’s just crunching numbers. A program is I/O bound if it … Read more
One thing you could do (this of course depends on what you are trying to accomplish) is: Store the necessary information (i.e. like a loop counter) in a spreadsheet or another permanent store(i.e. ScriptProperties). Have your script terminate every five minutes or so. Set up a time driven trigger to run the script every five … Read more
Rico Mariani, the .NET Performance guru, had an article on this very subject. It’s not as simple as one might suspect. The basic advice is this: If your pattern looks like: x = f1(…) + f2(…) + f3(…) + f4(…) that’s one concat and it’s zippy, StringBuilder probably won’t help. If your pattern looks like: … Read more
The scope of local variables should always be the smallest possible. In your example I presume str is not used outside of the while loop, otherwise you would not be asking the question, because declaring it inside the while loop would not be an option, since it would not compile. So, since str is not … Read more
Fastest way to determine if an integer’s square root is an integer